This invention relates to a work transfer mechanism usable in an automobile plant for transporting a panel, such as a door panel or the like, between fixtures. The mechanism, in its preferred form, comprises a carriage movable linearly along stationary guides extending between two transfer points. Two foldable arm structures are supported on the carriage for folding-unfolding movements separate from the carriage movement. A work-gripper platform is carried on the free ends of the foldable arm structures. The work-gripper platform includes vacuum cup devices engageable with the work to be transferred. Other types of work grippers can be used, e.g. magnets or jaw structures.
The foldable arm structures can extend into confined spaces within forming dies or support fixtures to enable the vacuum cup devices to grip and remove the work from the confined space. Carriage motion will usually be used to advance the arm structures into the confined space and then retract the arm structures out of the confined space.
During the carriage motion toward the discharge point, the foldable arm structures undergo a reverse folding-unfolding motion so that the supported work is transferred from one end of the carriage to the other end of the carriage. When the carriage arrives at the discharge point, the arm structures support the work at the other end of the carriage. Final motion of the carriage can be used to insert the work into a work station or other transfer point.
The transfer mechanism of this invention is designed to move the work between two confined spaces located relatively far apart, e.g. 20 feet.
The foldable arm structures have minimum overhang along the side edges of the carriage, such that the transfer mechanism requires a relatively narrow floor space.
The foldable arm structures are also advantageous in decelerating the work platform as it nears the end limits of its stroke, i.e. as it begins to pick up the workpiece or unload the workpiece. During the end stages of the work platform motion, the arm structures complete their unfolding motions in a relatively slow controlled fashion. During the major portion of the stroke, the work platform moves at a relatively high rate.
The transfer mechanism utilizes a combination of movements i.e. the carriage movement and the arm structure movement. The movements take place simultaneously, such that a relatively long total stroke distance can be achieved in a relatively short period of time, thereby resulting in relatively high cycle rates. Such high cycle rates are also due to the fact that the arm structures are relatively light low-mass structures that can be accelerated to high speeds with relatively modest size power mechanisms (motors).